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Featured researches published by David O. Freedman.


Annals of Internal Medicine | 2013

GeoSentinel surveillance of illness in returned travelers, 2007-2011.

Karin Leder; Joseph Torresi; Michael Libman; Jakob P. Cramer; Francesco Castelli; Patricia Schlagenhauf; Annelies Wilder-Smith; Mary E. Wilson; Jay S. Keystone; Eli Schwartz; Elizabeth D. Barnett; Frank von Sonnenburg; John S. Brownstein; Allen C. Cheng; Mark J. Sotir; Douglas H. Esposito; David O. Freedman

BACKGROUND International travel continues to increase, particularly to Asia and Africa. Clinicians are increasingly likely to be consulted for advice before travel or by ill returned travelers. OBJECTIVE To describe typical diseases in returned travelers according to region, travel reason, and patient demographic characteristics; describe the pattern of low-frequency travel-associated diseases; and refine key messages for care before and after travel. DESIGN Descriptive, using GeoSentinel records. SETTING 53 tropical or travel disease units in 24 countries. PATIENTS 42 173 ill returned travelers seen between 2007 and 2011. MEASUREMENTS Frequencies of demographic characteristics, regions visited, and illnesses reported. RESULTS Asia (32.6%) and sub-Saharan Africa (26.7%) were the most common regions where illnesses were acquired. Three quarters of travel-related illness was due to gastrointestinal (34.0%), febrile (23.3%), and dermatologic (19.5%) diseases. Only 40.5% of all ill travelers reported pretravel medical visits. The relative frequency of many diseases varied with both travel destination and reason for travel, with travelers visiting friends and relatives in their country of origin having both a disproportionately high burden of serious febrile illness and very low rates of advice before travel (18.3%). Life-threatening diseases, such as Plasmodium falciparum malaria, melioidosis, and African trypanosomiasis, were reported. LIMITATIONS Sentinel surveillance data collected by specialist clinics do not reflect healthy returning travelers or those with mild or self-limited illness. Data cannot be used to infer quantitative risk for illness. CONCLUSION Many illnesses may have been preventable with appropriate advice, chemoprophylaxis, or vaccination. Clinicians can use these 5-year GeoSentinel data to help tailor more efficient pretravel preparation strategies and evaluate possible differential diagnoses of ill returned travelers according to destination and reason for travel. PRIMARY FUNDING SOURCE Centers for Disease Control and Prevention.


Clinical Infectious Diseases | 2006

The Practice of Travel Medicine: Guidelines by the Infectious Diseases Society of America

David R. Hill; Charles D. Ericsson; Richard D. Pearson; Jay S. Keystone; David O. Freedman; Phyllis E. Kozarsky; Herbert L. DuPont; Frank J. Bia; Philip R. Fischer; Edward T. Ryan

David R. Hill, Charles D. Ericsson, Richard D. Pearson, Jay S. Keystone, David O. Freedman, Phyllis E. Kozarsky, Herbert L. DuPont, Frank J. Bia, Philip R. Fischer, and Edward T. Ryan National Travel Health Network and Centre and Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, England; Department of Medicine, University of Toronto, and Center for Travel and Tropical Medicine, Toronto General Hospital, Toronto, Ontario, Canada; Department of Internal Medicine, Clinical Infectious Diseases, University of Texas Medical School at Houston, Department of Internal Medicine, St. Luke’s Hospital, and Center for Infectious Diseases, University of Texas at Houston School of Public Health, and Department of Medicine, Baylor College of Medicine, Houston, Texas; Departments of Medicine and Pathology, Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia; Departments of Medicine and Epidemiology, Division of Geographic Medicine, University of Alabama at Birmingham, Birmingham; Department of Medicine, Infectious Diseases, Emory University School of Medicine, and 16 Division of Global Migration and Quarantine, Centers for Disease Control and Prevention, Atlanta, Georgia; Department of Medicine and Laboratory Medicine, Yale Medical School, New Haven, Connecticut; Department of Pediatrics, Division of General Pediatric and Adolescent Medicine, Mayo Clinic College of Medicine, and Mayo Eugenio Litta Children’s Hospital, Mayo Clinic, Rochester, Minnesota; and Department of Medicine, Division of Infectious Diseases, Harvard Medical School, Harvard School of Public Health, and Tropical and Geographic Medicine Center, Massachusetts General Hospital, Boston, Massachusetts


The Lancet | 2016

Zika virus and microcephaly: why is this situation a PHEIC?

David L. Heymann; Abraham Hodgson; Amadou A. Sall; David O. Freedman; J. Erin Staples; Fernando Althabe; Kalpana Baruah; Ghazala Mahmud; Nyoman Kandun; Pedro Fernando da Costa Vasconcelos; Silvia Bino; K U Menon

Fil: Heymann, David L. London School of Hygiene & Tropical Medicine; Reino Unido. The Royal Institute of International Affairs; Reino Unido


Emerging Infectious Diseases | 2008

Seasonality, Annual Trends, and Characteristics of Dengue among Ill Returned Travelers, 1997–2006

Eli Schwartz; Leisa H. Weld; Annelies Wilder-Smith; Frank von Sonnenburg; Jay S. Keystone; Kevin C. Kain; Joseph Torresi; David O. Freedman

Atypical patterns may indicate onset of epidemic activity.


The New England Journal of Medicine | 2008

Malaria Prevention in Short-Term Travelers

David O. Freedman

A family is planning a safari that includes 3 days in Cape Town, 3 days in Kruger National Park, South Africa, and 3 days in Victoria Falls, Zambia. The 31-year-old husband takes no medications, but recently he discontinued fluoxetine for depression. His 29-year-old wife is healthy and 15 weeks pregnant. Their 7-year-old child is in good health. How should the risk and prevention of malaria be managed in this family?


Journal of Travel Medicine | 2008

Gastrointestinal Infection Among International Travelers Globally

Zoe Greenwood; Jim Black; Leisa H. Weld; Daniel P. O’Brien; Karin Leder; Frank von Sonnenburg; Prativa Pandey; Eli Schwartz; Bradley A. Connor; Graham V. Brown; David O. Freedman; Joseph Torresi

BACKGROUND Data on relative rates of acquisition of gastrointestinal infections by travelers are incomplete. The objective of this study was to analyze infections associated with oral ingestion of pathogens in international travelers in relation to place of exposure. METHODS We performed a multicenter, retrospective observational analysis of 6,086 travelers ill enough with any gastrointestinal infection to seek medical care at a GeoSentinel clinic after completion of travel during 2000 to 2005. We determined regional and country-specific reporting rate ratios (RRRs) in comparison to risk in northern and western Europe. RESULTS Travel to sub-Saharan Africa (RRR = 282), South America (RRR = 203), and South Asia (RRR = 890) was associated with the greatest rate of gastrointestinal infections. RRRs were moderate (25-142) for travel to Oceania, the Middle East, North Africa, Central America, the Caribbean, and Southeast Asia. RRRs were least (<28) following travel to southern, central, and eastern Europe; North America; Northeast Asia; and Australasia. Income level of the country visited was inversely proportional to the RRR for gastrointestinal infection. For bacterial and parasitic infections examined separately, the regions group in the same way. RRRs could be estimated for 28 individual countries and together with regional data were used to derive a global RRR map for travel-related gastrointestinal infection. CONCLUSIONS This analysis of morbidity associated with oral ingestion of pathogens abroad determines which parts of the world currently are high-risk destinations.


American Journal of Tropical Medicine and Hygiene | 2013

Acute and Potentially Life-Threatening Tropical Diseases in Western Travelers—A GeoSentinel Multicenter Study, 1996–2011

Mogens Jensenius; Pauline V. Han; Patricia Schlagenhauf; Eli Schwartz; Philippe Parola; Francesco Castelli; F. von Sonnenburg; Louis Loutan; Karin Leder; David O. Freedman

We performed a descriptive analysis of acute and potentially life-threatening tropical diseases among 82,825 ill western travelers reported to GeoSentinel from June of 1996 to August of 2011. We identified 3,655 patients (4.4%) with a total of 3,666 diagnoses representing 13 diseases, including falciparum malaria (76.9%), enteric fever (18.1%), and leptospirosis (2.4%). Ninety-one percent of the patients had fever; the median time from travel to presentation was 16 days. Thirteen (0.4%) patients died: 10 with falciparum malaria, 2 with melioidosis, and 1 with severe dengue. Falciparum malaria was mainly acquired in West Africa, and enteric fever was largely contracted on the Indian subcontinent; leptospirosis, scrub typhus, and murine typhus were principally acquired in Southeast Asia. Western physicians seeing febrile and recently returned travelers from the tropics need to consider a wide profile of potentially life-threatening tropical illnesses, with a specific focus on the most likely diseases described in our large case series.


Clinical Infectious Diseases | 2010

Sex and Gender Differences in Travel-Associated Disease

Patricia Schlagenhauf; Lin H. Chen; Mary E. Wilson; David O. Freedman; David K. Tcheng; Eli Schwartz; Prativa Pandey; Rainer Weber; David Nadal; Christoph Berger; Frank von Sonnenburg; Jay S. Keystone; Karin Leder

BACKGROUND No systematic studies exist on sex and gender differences across a broad range of travel-associated diseases. METHODS Travel and tropical medicine GeoSentinel clinics worldwide contributed prospective, standardized data on 58,908 patients with travel-associated illness to a central database from 1 March 1997 through 31 October 2007. We evaluated sex and gender differences in health outcomes and in demographic characteristics. Statistical significance for crude analysis of dichotomous variables was determined using chi2 tests with calculation of odds ratios (ORs) and 95% confidence intervals (CIs). The main outcome measure was proportionate morbidity of specific diagnoses in men and women. The analyses were adjusted for age, travel duration, pretravel encounter, reason for travel, and geographical region visited. RESULTS We found statistically significant (P < .001) differences in morbidity by sex. Women are proportionately more likely than men to present with acute diarrhea (OR, 1.13; 95% CI, 1.09-1.38), chronic diarrhea (OR, 1.28; 95% CI, 1.19-1.37), irritable bowel syndrome (OR, 1.39; 95% CI, 1.24-1.57), upper respiratory tract infection (OR, 1.23; 95% CI, 1.14-1.33); urinary tract infection (OR, 4.01; 95% CI, 3.34-4.71), psychological stressors (OR, 1.3; 95% CI, 1.14-1.48), oral and dental conditions, or adverse reactions to medication. Women are proportionately less likely to have febrile illnesses (OR, 0.15; 95% CI, 0.10-0.21); vector-borne diseases, such as malaria (OR, 0.46; 95% CI, 0.41-0.51), leishmaniasis, or rickettsioses (OR, 0.57; 95% CI, 0.43-0.74); sexually transmitted infections (OR, 0.68; 95% CI 0.58-0.81); viral hepatitis (OR, 0.34; 95% CI, 0.21-0.54); or noninfectious problems, including cardiovascular disease, acute mountain sickness, and frostbite. Women are statistically significantly more likely to obtain pretravel advice (OR, 1.28; 95% CI, 1.23-1.32), and ill female travelers are less likely than ill male travelers to be hospitalized (OR, 0.45; 95% CI, 0.42-0.49). CONCLUSIONS Men and women present with different profiles of travel-related morbidity. Preventive travel medicine and future travel medicine research need to address gender-specific intervention strategies and differential susceptibility to disease.


Emerging Infectious Diseases | 2013

Travel-associated illness trends and clusters, 2000-2010.

Karin Leder; Joseph Torresi; John S. Brownstein; Mary E. Wilson; Jay S. Keystone; Elizabeth D. Barnett; Eli Schwartz; Patricia Schlagenhauf; Annelies Wilder-Smith; Francesco Castelli; Frank von Sonnenburg; David O. Freedman; Allen C. Cheng

Longitudinal data examining travel-associated illness patterns are lacking. To address this need and determine trends and clusters in travel-related illness, we examined data for 2000–2010, prospectively collected for 42,223 ill travelers by 18 GeoSentinel sites. The most common destinations from which ill travelers returned were sub-Saharan Africa (26%), Southeast Asia (17%), south-central Asia (15%), and South America (10%). The proportion who traveled for tourism decreased significantly, and the proportion who traveled to visit friends and relatives increased. Among travelers returning from malaria-endemic regions, the proportionate morbidity (PM) for malaria decreased; in contrast, the PM trends for enteric fever and dengue (excluding a 2002 peak) increased. Case clustering was detected for malaria (Africa 2000, 2007), dengue (Thailand 2002, India 2003), and enteric fever (Nepal 2009). This multisite longitudinal analysis highlights the utility of sentinel surveillance of travelers for contributing information on disease activity trends and an evidence base for travel medicine recommendations.


Sexually Transmitted Diseases | 2002

Sexual behavior of international travelers visiting Peru

Miguel M. Cabada; Juan Echevarría; Carlos Seas; Guillermo Narvarte; Frine Samalvides; David O. Freedman; Eduardo Gotuzzo

Background Sexual behavior of travelers to Latin America and the sexual behavior of US travelers in general are poorly characterized. Goal The goal of the study was to evaluate sexual risk factors of travelers to Peru. Study Design Anonymous written questionnaires were administered to 442/507 (87%) of the individuals approached in the international departures area of the Lima airport. Results Of the 442 respondents, 54 (12.2%) had new sex partners during their stay. Sex with a local partner (35/52; 67.3%) was more frequent than sex with other travelers (18/52; 34.6%) or with sex workers (4/52; 7.7%). Risk factors for a new sex partner included male sex (relative risk, 1.94), single marital status (relative risk, 2.59), duration of stay longer than 30 days (relative risk, 5.05), traveling alone or with friends (relative risk, 2.88), and bisexual orientation (relative risk, 4.94). Frequency of sexual activity among US travelers was greater than that among travelers from other countries (15.2% [22/145] versus 10.6% [30/282]; NS). Condoms were consistently used by 12/50 (24%) and sometimes used by 10/50 (20%), including 8/20 United States travelers and 13/29 travelers from other countries. Conclusion Behaviors and risk factors are similar to those described for travelers to Africa, Asia, and Eastern Europe. Behavior of US travelers did not differ from that of other travelers.

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